A passive keyless entry (PKE) system offers an increased level of convenience over a standard lock and key, for example, by providing the ability to access a secure building or device without having to find, insert, and turn a traditional key. A user may simply approach and touch a locked PKE lock and with little if any pause, the lock grants this user access if they are carrying an authorized token.
A PKE system is currently used in an automotive application and may offer increased convenience by identifying drivers and unlocking the car as they approach and grab the handle. Automotive access is traditionally given by inserting a key into the lock or by pushing buttons on a traditional remote keyless entry (RKE) system. In contrast, a PKE system grants access with reduced user interaction through the use of a hands free token carried by the driver.
Several technical challenges have been encountered during the engineering of a radio frequency (RF) PKE system, for example, for use in a residential lock. The desired basic perceived behavior of the PKE system in a residential application may be as follows: 1) the user approaches and touches the lock; 2) the lock authenticates the user with a minimally perceived delay; 3) the lock unlocks; 4) the lock may not operate if the authorized user is outside a desired range and the lock is touched by another, unauthorized, user; 5) the lock may not operate if the authorized user is on the inside of the house, and the lock is touched on the outside by an unauthorized user; and 6) the battery powered lock needs several months or more worth of battery life to prevent inconvenient and costly battery changes. 7) if a PKE fob is used, battery power needs to be over a year. 8) the lock can provide anytime, or configurable limited time, access control. 9) the lock has the ability to be locked without a remote access device
Indeed, as will be appreciated by those skilled in the art, with respect to the above desired basic perceived behavior of the PKE system in a residential application, primary challenges to be addressed include items 1 (Simplicity), 2 (speed), 4 (distance), 5 (location), 6-7 (battery life), and 8-9 (convenience). Accordingly, it may be desirable to improve authentication speed, proximity measurement, location determination, decrease power consumption, and increase convenience for example.